Optimising the use of electronic health records to estimate the incidence of rheumatoid arthritis in primary care: what information is hidden in free text?

Table 1 Summary of indicator markers and keyword groups

Indicator codes – based on code	Example codes
Indicator codes – based on code	(full list available in Additional file 1)
Inflammatory arthritis diagnosis	Seronegative arthritis, polyarthropathy, arthralgia of multiple joints
Rheumatoid Factor test	RhF , latex test, Rose Waller (included regardless of result)
Synovitis	Synovitis
DMARD prescription	List of drug names drawn up from British National Formulary
Referral to Rheumatology	Rheum. disorder monitoring, Rheum. treatment change, Rheum. management plan given, Under care of rheumatologist
Joint signs and symptoms	Joint abnormal, joint swelling, reduced joint movement, joint movement painful, joint stiffness, inflammation joint, etc.
Keyword groups – based on text	Example search terms
Keyword groups – based on text	Full list available in Additional file 2
Rheumatoid Arthritis	RA. RhA, rheum arth,
Positive rheumatoid factor test	Positive RhF , rheum fac +
Inflammatory arthritis	Polyarthitis, seronegative arthritis, inflammatory arthritis
Synovitis	Synovitis

ISSN: 1471-2288